[Cnye92]

So i recently rebuilt my 400ex with a 440 big bore kit. I installed a new cylinder piston rings racing manual tensioner and all new gaskets and o rings. I set the valve clearance to the service manual specs and was getting 150 psi on the compression test. Wouldnt start. So i tinkered woth the valves until i got it 120 psi. (Partzilla says should be between 100-128). And it still wont start. Ive got a brand new spark plug. Its getting fuel and everything. My question is what should i do about this. Should i set them back to .004 int and .005 ex and leave it at 150 psi? Ive also been hearing that i should jet the carb. What sizes should i use? Ive got so much time and money into this project and just am completely stuck right now. Someone please help...

 

[fishfiles]

Cnye92 , I seen your PM , I am not a EX 440 big bore kind of guy ,Slammed Ranger seems most knowledgable with what you got ------ but I will try to help you out , I know you need three things for it to run , compression , fuel and fire , sounds like you got compression , you say you have fuel and " everything " , is " everything " fire at the plug when grounded against the engine , if you do also have fire , I would look to timing as it sounds like you rebuilt the engine to install a big bore kit , maybe the cam is 180 degrees out of time or a tooth off

 

[SlammedRanger]

So from what im reading there is a few questions. Do you still have the stock cam? And if so did you put the spring and plunger for auto decompression mechanism back in the hole in the head casting? If not thats why its not starting. If you have fuel, spark, and compression it should at the very least pop. If it pops every revolution you are 180° out if time. The cam lobes should be facing down with the engine at TDC. With the | T mark lined up can be at bottom of stroke or top of stroke. You need to pull the plug and use a long screw driver or something to verify its at the top of the stroke(Do Not Use Something You Can Drop In On Accident) been there done that. Wasnt a shinning moment lol. Aside from that the 150 psi isnt that bad. The manual is telling you the stock piston and compression number which is 128. But since i dont think there is a 440 piston on the market that is stock compression so your probably 10:1 or 11:1 something like that the number will be higher. Set your valves per factory spec. My 416 pushes 145-148 psi compression and im 11:1.

Welcome to the forums!

 

[SlammedRanger]

One other thing bud. Please refrain from duplicate posts. You will soon learn that this forum dosnt ever push threads aside and never respond to them. Just one well placed thread will get your answers. I removed the other thread with the same title since this one was in the more proper catagory.

 

[Cnye92]

Thank you slammed ranger. Sorry about the duplicate post. Just been stressing hard about this build. So anyways. Im 99 percent sure its in time. And i lut the spark plug against the frame. Not a crazy arc or anything but she is sparking. As far as the cam and decompression yes i did put the spring and decompression mech. back in and it is the stock cam. So do i need a stage one? And also like i was saying ive had mutliple differemt answers about the jetting size. Some say go bigger. Some say go smaller. Im just getting alot of different answers amd dont know for myself which is true and which is not.

 

[Carolynskii]

First things first .... spray starting fluid in the carb and see if it try's to start ... if it does it's your carb or fuel not getting to carb

 

[Cnye92]

First things first .... spray starting fluid in the carb and see if it try's to start ... if it does it's your carb or fuel not getting to carb

It doesnt. Doesnt sputter doesnt pop. Nothing hinting towards any ignition whatsoever. Just turns over.

 

[SlammedRanger]

No worries! Your new here its all good. You only mentioned the spring. Did you put the hollow pin(plunger) back in on top of the spring? And you will 100% need bigger jets. No chance you would need smaller. And you dont have to do an aftermarket cam. If you want to you can but its not necessary or anything.

 

[Cnye92]

No worries! Your new here its all good. You only mentioned the spring. Did you put the hollow pin(plunger) back in on top of the spring? And you will 100% need bigger jets. No chance you would need smaller. And you dont have to do an aftermarket cam. If you want to you can but its not necessary or anything.

Yes i put the plunger back in too. Sorry i didnt mention it. But yeah its in there. And ok any reccomendation on the jet sizes for main and pilot? I was told 160-165 main and 45 pilot.

 

[SlammedRanger]

Yep 45 pilot for sure. What other mods do you have? Full pipe? Slip-on? Any intake mods? Airbox lid removed? Give me anything that gets more air out or in the engine.

 

[Cnye92]

Yep 45 pilot for sure. What other mods do you have? Full pipe? Slip-on? Any intake mods? Airbox lid removed? Give me anything that gets more air out or in the engine.

It has a slip on hmf. A k&n high flow filter. A racing tensioner. And the 440 big bore piston rings and cylinder. That should be about it.

 

[SlammedRanger]

Air box lid still on?

 

[Cnye92]

Air box lid still on?

Yes. I ride mountains. And theres alot of rain and stuff here so yeah i dont ride with it off.

 

[SlammedRanger]

Ok. I would be betting 175-180-185 should get you real close.

 

[Cnye92]

Ok. I would be betting 175-180-185 should get you real close.

So a 180 should be good then.

 

[Cnye92]

Ok. I would be betting 175-180-185 should get you real close.

Also it was recommended to me that i put the jet needle one ring down. What are your thoughts on this?

 

[SlammedRanger]

Yeah it will help your mid power range. What altitude would you say your riding in? You mentioned mountains. Just noticed that. High altitude jetting will be smaller then my suggestions.

 

[Cnye92]

Yeah it will help your mid power range. What altitude would you say your riding in? You mentioned mountains. Just noticed that. High altitude jetting will be smaller then my suggestions.

1200 ft. Nothing major.

 

[SlammedRanger]

Yeah ok thats not anything. Im at around 700 ft. The 180 should be really close.

 

[Cnye92]

Yeah ok thats not anything. Im at around 700 ft. The 180 should be really close.

I ordered a 178 main and 45 pilot. It shoud ship tomorrow. Also i gkt the bike running. Adjusted the valves back to factory spec did a compression test eith 140 psi. Bought some 91 octane fuel w no ethanol in it. And after some tinkering it fired righr up. Thanks to all the guys that lent their hands. You guys are awesome.